Combined cycle power plant with fuel reformer

ABSTRACT

Provided is turbine plant using methanol as fuel in which working fluid is compressed by compressor  1  and led into combustor  2 . A mixture of H 2  and CO 2  as fuel added with O 2  is burned to generate high temperature gas, which works at high temperature turbine  3 , flows through heat exchangers  4, 5  and returns partly to the compressor  1  and enters partly low pressure turbine  7  of bottoming system to work. Condensed water from condenser  9  of the bottoming system is pressurized by pressure pump  10  and flows through the heat exchangers  4, 5  to become high temperature steam and to work at high pressure turbine  6 . Exhaust gas thereof is mixed into the combustor  2 . A mixture of methanol and water is supplied into reformer  13  to absorb heat from the heat exchanger  4  to be reformed into H 2  and CO 2 , which is supplied into the combustor  2 . A high temperature portion of the high temperature turbine  3  is cooled by cooling medium extracted from compressor  1  outlet and high pressure turbine  6  outlet thereby reliability of the high temperature turbine  3  is enhanced.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a combined cycle power plant usingfossil fuel including methanol and the like.

2. Description of the Prior Art

FIG. 28 is a diagrammatic view of a prior art combined cycle powerplant, using pure oxygen as oxidizing agent and methane as fuel, whichhas been disclosed from the Graz Institute of Technology. In the figure,numeral 1 designates a compressor, which compresses a mixture gas ofsteam and carbon dioxide as working fluid to a pressure decided by anentire system optimization study. Numeral 2 designates a combustor,which is supplied with oxygen needed for an equivalent combustion of themethane as fuel to generate a high temperature high pressure combustiongas, wherein components of the combustion gas are carbon dioxide andsteam. Numeral 3 designates a high temperature gas turbine, whichexpands the high temperature high pressure combustion gas to obtain awork. Numerals 4, 5 designate first and second heat exchangers,respectively, and a condensed water produced at a bottoming system froman exhaust gas of the high temperature gas turbine 3 extracted at amidpoint between the first and second heat exchangers 4, 5 is heated atthe first and second heat exchangers 4, 5 to generate a high temperaturehigh pressure steam. Numeral 6 designates a high pressure steam turbine,which expands the high temperature high pressure steam generated at thefirst and second heat exchangers 4, 5 approximately to an inlet pressureof the combustor 2 to obtain a work as well as to send the steam soexpanded to be mixed into an inlet of the combustor 2. Remaining exhauststeam from the high temperature gas turbine 3 which has passed throughthe first and second heat exchangers 4, 5 with its temperature havingbeen reduced returns to an inlet of the compressor 1.

Numeral 7 designates a low pressure turbine, which expands thecombustion gas extracted at the midpoint between the first and secondheat exchangers 4, 5 approximately to a vacuum to obtain a work. Numeral8 designates a carbon dioxide compressor (vacuum pump), which compressesthe mixture gas the containing the entire amount of the carbon dioxidegenerated at the combustor 2 approximately to the atmospheric pressureto thereby discharge the carbon dioxide as a combustion-generatedproduct outside of the system. Numeral 9 designates a condenser, inwhich an outlet gas of the low pressure turbine 7 which has beenpressure-reduced by the carbon dioxide compressor (vacuum pump) 8 isheat-exchanged by the sea water or the like to be temperature-reduced sothat the steam is liquefied. The liquefied water is pressurized by apressure pump 10 to be fed into the first and second heat exchangers 4,5 to thereby become the high temperature high pressure steam. The steamas the combustion-generated product which has been expanded at the lowpressure turbine 7 is mostly liquefied to water at the condenser 9, anda remaining portion thereof becomes a drain in the process of beingcompressed by the vacuum pump 8 approximately to the atmosphericpressure to be discharged outside of the system.

In the prior art combined cycle power plant as mentioned above, whilethe high temperature combustion gas having the component of carbondioxide and steam is obtained using the methane as fuel and oxygen, itis also possible to use a methanol (CH₃OH) fuel or other fossil fuels,but in this case, it has been a problem that the gross thermalefficiency is low.

SUMMARY OF THE INVENTION

In view of the problem in the prior art, therefore, it is an object ofthe present invention to improve the prior art combined cycle powerplant using the methane fuel so that a turbine plant using methanol fuelor other fossil fuels is obtained, gross thermal efficiency thereof ismore enhanced than that of the prior art combined cycle power plant andreliability of the turbine plant is also enhanced.

In order to attain said object, the present invention provides thefollowing aspects (1) to (27):

(1) A turbine plant comprising a compressor for compressing a mixturegas of steam and carbon dioxide as a working fluid; a combustor forburning a fuel together with the working fluid from the compressor addedwith oxygen; a high temperature turbine for expanding a combustion gasfrom the combustor to obtain a work; a bottoming system for driving alow pressure turbine by an exhaust gas from the high temperature turbineto obtain a work; a heat exchanger for heating a condensed water fromthe bottoming system to a high temperature steam by a heat exchange withthe exhaust gas from the high temperature turbine and for leading theexhaust gas (after it is used for the heat exchange) into an inlet ofthe compressor as the working fluid; and a high pressure turbine forexpanding the high temperature steam of the bottoming system heated atthe heat exchanger to obtain a work and for mixing the steam so expandedinto the combustor. In addition, a reformer is provided for receiving amixture of methanol and water to be reformed into hydrogen and carbondioxide by heat absorbed at the heat exchanger and for supplying thehydrogen and carbon dioxide into the combustor as a fuel; and a hightemperature turbine cooling system is provided for extracting theworking fluid from an outlet of the compressor and an outlet of the highpressure turbine to be led into a high temperature portion of the hightemperature turbine for cooling thereof as a cooling medium.

In the invention of aspect (1), the reformer can reform the mixture ofmethanol (CH₃OH) and water (H₂O) into hydrogen (H₂) and carbon dioxide(CO₂) so that the gross thermal efficiency is enhanced. Further, thehigh temperature portion of the high temperature turbine can be cooledby the high temperature turbine cooling system so that reliability ofthe high temperature turbine is enhanced.

(2) A turbine plant as mentioned in aspect (1) above, characterized inthat the compressor comprises a low pressure compressor and a highpressure compressor. Between the low pressure compressor and the highpressure compressor, a passage is provided for flowing therethrough theworking fluid via an intercooler. A portion of the condensed water fromthe bottoming system is mixed into the intercooler under pressure.

In the invention of aspect (2), in addition to the effect of theinvention of aspect (1), the low pressure compressor outlet gas istemperature-reduced so that the compression power of the high pressurecompressor is reduced so that the gross thermal efficiency is enhanced.Also, the high pressure compressor outlet temperature is reduced so thatthereby reliability of the disc strength of the high pressure compressoroutlet portion is enhanced. Further, the combustor inlet gas temperatureis reduced so that reliability of the high temperature portion of thecombustor is also enhanced.

(3) A turbine plant as mentioned in aspect (1) above, characterized inthat there is provided between the outlet of the compressor and an inletof the combustor a regenerative heat exchanger for elevating a combustorinlet gas temperature by a heat exchange between an outlet gas of thecompressor and the exhaust gas from the high temperature turbine.

In the invention of aspect (3), in addition to the effect of theinvention of aspect (1), there is provided the regenerative heatexchanger so that the combustor inlet gas temperature is elevated, thefuel flow rate is reduced and the gross thermal efficiency is enhanced.

(4) A turbine plant as mentioned in aspect (3) above, characterized inthat the compressor comprises a low pressure compressor and a highpressure compressor. Between the low pressure compressor and the highpressure compressor, a passage is provided for flowing therethrough theworking fluid via an intercooler, and a portion of the condensed waterfrom the bottoming system is mixed into the intercooler under pressure.

In the invention of aspect (4), in addition to the effect of theinvention of aspect (3), the low pressure compressor outlet gas istemperature-reduced and the compression power of the high pressurecompressor is reduced so that the gross thermal efficiency is enhanced.Also, the high pressure compressor outlet temperature is reduced so thatreliability of the disc strength of the high pressure compressor outletportion is enhanced. Further, the combustor inlet gas temperature isreduced so that reliability of the high temperature portion of thecombustor is enhanced.

(5) A turbine plant as mentioned in aspect (1) above, characterized inthat a heated steam of the bottoming system from the heat exchanger isdirectly mixed into the combustor via a passage where the high pressureturbine is eliminated. The cooling medium of the high temperatureturbine is extracted from the outlet of the compressor and a hightemperature gas side of the heat exchanger.

In the invention of aspect(5), in addition to the effect of theinvention of aspect (1), the high pressure turbine is eliminated so thatthe construction cost can be reduced.

(6) A turbine plant as mentioned in aspect (5) above, characterized inthat the compressor comprises a low pressure compressor and a highpressure compressor. Between the low pressure compressor and the highpressure compressor, a passage is provided for flowing therethrough theworking fluid via an intercooler, and a portion of the condensed waterfrom the bottoming system is mixed into the intercooler under pressure.

In the invention of aspect (6), in addition to the effect of theinvention of aspect (5), the low pressure compressor outlet gas istemperature-reduced and the compression power of the high pressurecompressor is reduced so that the gross thermal efficiency is enhanced.Also, the high pressure compressor outlet temperature is reduced so thatreliability of the disc strength of the high pressure compressor outletportion is enhanced. Further, the combustor inlet gas temperature isreduced, so that reliability of the high temperature portion of thecombustor is also enhanced.

(7) A turbine plant as mentioned in aspect (1) above, characterized inthat the bottoming system comprises only a water condensing systemhaving no low pressure turbine and no CO₂ compressor therein, and isconstructed such that the condensed water from the water condensingsystem is partly led into the inlet of the compressor as the workingfluid. The condensed water from the water condensing system is partlyheat-exchanged with the exhaust gas from the high temperature turbine atthe heat exchanger. The high temperature steam generated by the heatexchange is directly mixed into the combustor via a passage where thehigh pressure turbine is eliminated, and the exhaust gas from the hightemperature turbine after so heat-exchanged is led into the watercondensing system of the bottoming system. The high temperature turbinecooling system extracts the cooling medium from the outlet of thecompressor and a high temperature gas side of the heat exchanger.

In the invention of aspect (7), in addition to the effect of theinvention of aspect (1), the high pressure turbine, and the low pressureturbine and the CO₂ compressor of the bottoming system are eliminated sothat the construction cost can be reduced largely. Further, thecompressor inlet temperature is reduced, so that the power of thecompressor is reduced and the gross thermal efficiency is enhanced.

(8) A turbine plant as mentioned in aspect (7) above, characterized inthat the compressor comprises a low pressure compressor and a highpressure compressor. Between the low pressure compressor and the highpressure compressor, a passage is provided for flowing therethrough theworking fluid via an intercooler, and a portion of the condensed waterfrom the water condensing system is mixed into the intercooler underpressure.

In the invention of aspect (8), in addition to the effect of theinvention of aspect (7), the low pressure compressor outlet gas istemperature-reduced and the compression power of the high pressurecompressor is reduced so that the gross thermal efficiency is enhanced.Also, the high pressure compressor outlet temperature is reduced, sothat reliability of the disc strength of the high pressure compressoroutlet portion is enhanced. Further, the combustor inlet gas temperatureis reduced, so that reliability of the high temperature portion of thecombustor is enhanced.

(9) A turbine plant as mentioned in aspect (3) above, characterized inthat the bottoming system comprises only a water condensing systemhaving no low pressure turbine and no CO₂ compressor therein. Thecondensed water from the water condensing system is partly led into theinlet of the compressor as the working fluid, and the exhaust gas fromthe high temperature turbine after being heat-exchanged is led into thewater condensing system.

In the invention of aspect (9), the low pressure turbine and the CO₂compressor of the bottoming system are eliminated, so that theconstruction cost can be reduced more than the plant of the invention ofaspect (3). Further, the compressor inlet temperature is reduced and thepower of the compressor is reduced so that by the gross thermalefficiency is enhanced.

(10) A turbine plant as mentioned in aspect (9) above, characterized inthat the compressor comprises a low pressure compressor and a highpressure compressor. Between the low pressure compressor and the highpressure compressor, a passage is provided for flowing therethrough theworking fluid via an intercooler, and a portion of the condensed waterfrom the water condensing system is mixed into the intercooler underpressure.

In the invention of aspect (10), in addition to the effect of theinvention of aspect (9), the low pressure compressor outlet gas istemperature-reduced and the compression power of the high pressurecompressor is reduced so that the gross thermal efficiency is enhanced.Also, the high pressure compressor outlet temperature is reduced, sothat reliability of the disc strength of the high pressure compressoroutlet portion is enhanced. Further, the combustor inlet gas temperatureis reduced so that reliability of the high temperature portion of thecombustor is enhanced.

(11) A turbine plant as mentioned in aspect (1) above, characterized inthat the bottoming system comprises a water condensing system and a CO₂compressor having no low pressure turbine therein. The condensed waterfrom the water condensing system is partly led into the inlet of thecompressor as the working fluid. The condensed water from the watercondensing system is partly heat-exchanged with the exhaust gas from thehigh temperature turbine at the heat exchanger. The high temperaturesteam generated by the heat exchange is directly mixed into thecombustor via a passage where the high pressure turbine is eliminated.The exhaust gas from the high temperature turbine after beingheat-exchanged is led into the water condensing system, and the coolingmedium of the high temperature turbine is extracted from the outlet ofthe compressor and a high temperature gas side of the heat exchanger.

In the invention of aspect (11), in addition to the effect of theinvention of aspect (1), the high temperature turbine outlet pressure isreduced and the high temperature turbine outlet temperature is reduced,so that the anti-creep life of the final stage moving blade of the hightemperature turbine can be elongated. Also, the high pressure turbineand the low pressure turbine are eliminated, so that the constructioncost is reduced. Further, the compressor inlet temperature is reducedand the power of the compressor is reduced so that the gross thermalefficiency is enhanced.

(12) A turbine plant as mentioned in aspect (11) above, characterized inthat the compressor comprises a low pressure compressor and a highpressure compressor. Between the low pressure compressor and the highpressure compressor, a passage is provided for flowing therethrough theworking fluid via an intercooler, and a portion of the condensed waterfrom the water condensing system is mixed into the intercooler underpressure.

In the invention of aspect (12), in addition to the effect of theinvention of aspect (11), the low pressure compressor outlet gas istemperature-reduced and the compression power of the high pressurecompressor is reduced so that the gross thermal efficiency is enhanced.Also, the high pressure compressor outlet. temperature is reduced, sothat reliability of the disc strength of the high pressure compressoroutlet portion is enhanced. Further, the combustor inlet gas temperatureis reduced, so that reliability of the high temperature portion of thecombustor is enhanced.

(13) A turbine plant as mentioned in aspect (3) above, characterized inthat the bottoming system comprises a water condensing system and a CO₂compressor having no low pressure turbine therein, and is constructedsuch that the condensed water from the bottoming system is partly ledinto the inlet of the compressor as the working fluid. The exhaust gasfrom the high temperature turbine after being heat-exchanged at the heatexchanger is led into a condenser of the bottoming system.

In the invention of aspect (13), in addition to the effect of theinvention of aspect (3), the high temperature turbine outlet pressure isreduced and the high temperature turbine outlet temperature is reducedso that the anti-creep life of the final stage moving blade of the hightemperature turbine can be elongated. Also, the low pressure turbine iseliminated so that the construction cost is reduced. Further, thecompressor inlet temperature is reduced and the power of the compressoris reduced so that the gross thermal efficiency is enhanced.

(14) A turbine plant as mentioned in aspect (13) above, characterized inthat the compressor comprises a low pressure compressor and a highpressure compressor. Between the low pressure compressor and the highpressure compressor, a passage is provided for flowing therethrough theworking fluid via an intercooler, and a portion of the condensed waterfrom the bottoming system is mixed into the intercooler under pressure.

In the invention of aspect (14), in addition to the effect of theinvention of aspect (13), the low pressure compressor outlet gas istemperature-reduced and the compression power of the high pressurecompressor is reduced so that the gross thermal efficiency is enhanced.Also, the high pressure compressor outlet temperature is reduced so thatreliability of the disc strength of the high pressure compressor outletportion is enhanced. Further, the combustor inlet gas temperature isreduced so that reliability of the high temperature portion of thecombustor is enhanced.

(15) A turbine plant comprising a compressor for compressing a mixturegas of steam and carbon dioxide as a working fluid; a combustor forburning a fossil fuel including methanol together with the working fluidfrom the compressor added with oxygen; a high temperature turbine forexpanding a combustion gas from the combustor to obtain a work; abottoming system for driving a low pressure turbine by an exhaust gasfrom the high temperature turbine to obtain a work; a heat exchanger forheating a condensed water from the bottoming system to a hightemperature steam by a heat exchange with the exhaust gas from the hightemperature turbine and for leading the exhaust gas (after it is usedfor the heat exchange) into an inlet of the compressor as the workingfluid; and a high pressure turbine for expanding the high temperaturesteam of the bottoming system heated at the heat exchanger to obtain awork and for mixing the steam so expanded into the combustor. Thecompressor comprises a low pressure compressor and a high pressurecompressor and is constructed such that, between the low pressurecompressor and the high pressure compressor, a passage is provided forflowing therethrough the working fluid via an intercooler. A portion ofthe condensed water from the bottoming system is mixed into theintercooler under pressure. A high temperature turbine cooling system isprovided for extracting the working fluid from an outlet of the highpressure compressor and an outlet of the high pressure turbine to be ledinto a high temperature portion of the high temperature turbine forcooling thereof as a cooling medium.

In the invention of aspect (15), the low pressure compressor outlet gasis temperature-reduced and the compression power is reduced so that thegross thermal efficiency is enhanced and reliability of the discstrength of the high pressure compressor outlet portion is enhanced.Also, the combustor inlet gas temperature is reduced so that reliabilityof the high temperature portion of the combustor is enhanced. Further,by the high temperature turbine cooling system, reliability of the hightemperature turbine is also enhanced. Also, in the invention of aspect(15), not only the methanol fuel but also other fossil fuels can beused, and the surplus gas generated at an iron making plant etc. or thecoal gasified fuel will be effective.

(16) A turbine plant as in the prior art, characterized in that betweenthe outlet of the compressor and an inlet of the combustor, aregenerative heat exchanger is provided for elevating a combustor inletgas temperature by a heat exchange between an outlet gas of thecompressor and the exhaust gas from the high temperature turbine. A hightemperature turbine cooling system is provided for extracting theworking fluid from an outlet of the compressor and an outlet of the highpressure turbine to be led into a high temperature portion of the hightemperature turbine for cooling thereof as a cooling medium.

In the invention of aspect (16), the combustor inlet gas temperature iselevated by the regenerative heat exchanger and the fuel flow rate isreduced so that the gross thermal efficiency is enhanced. Also, the hightemperature portion of the high temperature turbine is cooled by thehigh temperature turbine cooling system so that reliability of the hightemperature turbine is enhanced. Also, in the invention of aspect (16),not only the methanol fuel but also other fossil fuels can be used, andthe surplus gas generated at an iron making plant etc. or the coalgasified gas will be effective.

(17) A turbine plant as mentioned in aspect (16) above, characterized inthat the compressor comprises a low pressure compressor and a highpressure compressor. Between the low pressure compressor and the highpressure compressor, a passage is provided for flowing therethrough theworking fluid via an intercooler, and a portion of the condensed waterfrom the bottoming system is mixed into the intercooler under pressure.

In the invention of aspect (17), in addition to the effect of theinvention of aspect (16), the low pressure compressor outlet gas istemperature-reduced and the compression power of the high pressurecompressor is reduced so that the gross thermal efficiency is enhanced.Also, the high pressure compressor outlet temperature is reduced so thatreliability of the disc strength of the high pressure compressor outletportion is enhanced. Further, the combustor inlet gas temperature isreduced so that reliability of the high temperature portion of thecombustor is enhanced.

(18) A turbine plant as in the prior art, characterized in that a heatedsteam of the bottoming system from the heat exchanger is directly mixedinto the combustor via a passage where the high pressure turbine iseliminated. A high temperature turbine cooling system for extracting theworking fluid from an outlet of the compressor and a high temperaturegas side of the heat exchanger to be led into a high temperature portionof the high temperature turbine for cooling thereof as a cooling medium.

In the invention of aspect (18), the high pressure turbine is eliminatedso that the construction cost can be reduced more than the prior art.Also, the high temperature portion of the high temperature turbine iscooled by the high temperature turbine cooling system so thatreliability of the high temperature turbine is enhanced. Also, in theinvention of aspect (18), not only the methanol fuel but also otherfossil fuels can be used, and the surplus gas generated at an ironmaking plant etc. or the coal gasified fuel will be effective.

(19) A turbine plant as mentioned in aspect (18) above, characterized inthat the compressor comprises a low pressure compressor and a highpressure compressor. Between the low pressure compressor and the highpressure compressor, a passage is provided for flowing therethrough theworking fluid via an intercooler, and a portion of the condensed waterfrom the bottoming system is mixed into the intercooler under pressure.

In the invention of aspect (19), in addition to the effect of theinvention of aspect (18), the low pressure compressor outlet gas istemperature-reduced and the compression power of the high pressurecompressor is reduced so that the gross thermal efficiency is enhanced.Also, the high pressure compressor outlet temperature is reduced so thatreliability of the disc strength of the high pressure compressor outletportion is enhanced. Further, the combustor inlet gas temperature isreduced so that reliability of the high temperature portion of thecombustor is enhanced.

(20) A turbine plant as in the prior art, characterized in that thebottoming system comprises only a water condensing system having no lowpressure turbine and no CO₂ compressor therein, and is constructed suchthat the condensed water from the water condensing system is partly ledinto the inlet of the compressor as the working fluid. The condensedwater from the water condensing system is partly heat-exchanged with theexhaust gas from the high temperature turbine at the heat exchanger. Thehigh temperature steam generated by the heat exchange is directly mixedinto the combustor via a passage where the high pressure turbine iseliminated, and the exhaust gas from the high temperature turbine afterso heat-exchanged is led into the water condensing system of thebottoming system. A high temperature turbine cooling system is providedfor extracting the working fluid from an outlet of the compressor and ahigh temperature gas side of the heat exchanger to be led into a hightemperature portion of the high temperature turbine for cooling thereofas a cooling medium.

In the invention of aspect (20), the high pressure turbine, the lowpressure turbine and the CO₂ compressor are eliminated so that theconstruction cost can be reduced more than the prior art plant. Also,the compressor inlet temperature is reduced and the power of thecompressor is reduced so that the gross thermal efficiency is enhanced.Also, the high temperature portion of the high temperature turbine iscooled effectively by the high temperature turbine cooling system sothat reliability of the high temperature turbine is enhanced. Also, inthe invention of aspect (20), not only the methanol fuel but also otherfossil fuels can be used, and the surplus gas generated at an ironmaking plant etc. or the coal gasified fuel will be effective.

(21) A turbine plant as mentioned in aspect (20) above, characterized inthat the compressor comprises a low pressure compressor and a highpressure compressor. Between the low pressure compressor and the highpressure compressor, a passage is provided for flowing therethrough theworking fluid via an intercooler, and a portion of the condensed waterfrom the bottoming system is mixed into the intercooler under pressure.

In the invention of aspect (21), in addition to the effect of theinvention of aspect (20), the low pressure compressor outlet gas istemperature-reduced and the compression power of the high pressurecompressor is reduced so that the gross thermal efficiency is enhanced.Also, the high pressure compressor outlet temperature is reduced so thatreliability of the disc strength of the high pressure compressor outletportion is enhanced. Further, the combustor inlet gas temperature isreduced so that reliability of the high temperature portion of thecombustor is enhanced.

(22) A turbine plant as mentioned in aspect (16) above, characterized inthat the bottoming system comprises only a water condensing systemhaving no low pressure turbine and no CO₂ compressor therein, and isconstructed such that the condensed water from the bottoming system ispartly led into the inlet of the compressor as the working fluid. Theexhaust gas from the high temperature turbine after being heat-exchangedat the heat exchanger is led into a condenser of the bottoming system.

In the invention of aspect (22), in addition to the effect of theinvention of aspect (16), the low pressure turbine and the CO₂compressor are eliminated so that the construction cost can be reducedmore than the invention of aspect (16). Also, the compressor inlettemperature is reduced and the power of the compressor is reduced sothat the gross thermal efficiency is enhanced.

(23) A turbine plant as mentioned in aspect (22) above, characterized inthat the compressor comprises a low pressure compressor and a highpressure compressor. Between the low pressure compressor and the highpressure compressor, a passage is provided for flowing therethrough theworking fluid via an intercooler, and a portion of the condensed waterfrom the bottoming system is mixed into the intercooler under pressure.

In the invention of aspect (23), in addition to the effect of theinvention of aspect (22), the low pressure compressor outlet gas istemperature-reduced and the compression power of the high pressurecompressor is reduced so that the gross thermal efficiency is enhanced.Also, the high pressure compressor outlet temperature is reduced so thatreliability of the disc strength of the high pressure compressor outletportion is enhanced. Further, the combustor inlet gas temperature isreduced so that reliability of the high temperature portion of thecombustor is enhanced.

(24) A turbine plant as in the prior art, characterized in that thebottoming system comprises a water condensing system and a CO₂compressor having no low pressure turbine therein, and is constructedsuch that the condensed water from the water condensing system is partlyled into the inlet of the compressor as the working fluid. The condensedwater from the water condensing system is partly heat-exchanged with theexhaust gas from the high temperature turbine at the heat exchanger. Thehigh temperature steam generated by the heat exchange is directly mixedinto the combustor via a passage where the high pressure turbine iseliminated, and the exhaust gas from the high temperature turbine afterbeing heat-exchanged is led into the water condensing system of thebottoming system. A high temperature turbine cooling system is providedfor extracting the working fluid from an outlet of the compressor and ahigh temperature gas side of the heat exchanger to be led into a hightemperature portion of the high temperature turbine for cooling thereofas a cooling medium.

In the invention of aspect (24), the high temperature turbine outletpressure is reduced and the high temperature turbine outlet temperatureis reduced so that the anti-creep life of the final stage moving bladeof the high temperature turbine can be elongated. Also, the highpressure turbine and the low pressure turbine are eliminated so that theconstruction cost can be reduced. Also, the high temperature portion ofthe high temperature turbine is cooled by the high temperature turbinecooling system so that reliability of the high temperature turbine isenhanced.

Further, in the invention of aspect (24), not only the methanol fuel butalso other fossil fuels can be used, and the surplus gas generated at aniron making plant etc. or the coal gasified fuel will be effective.

(25) A turbine plant as mentioned in aspect (24) above, characterized inthat the compressor comprises a low pressure compressor and a highpressure compressor. Between the low pressure compressor and said highpressure compressor, a passage is provided for flowing therethrough theworking fluid via an intercooler. A portion of the condensed water fromthe bottoming system is mixed into the intercooler under pressure.

In the invention of aspect (25), in addition to the effect of theinvention of aspect (24), the low pressure compressor outlet gas istemperature-reduced and the compression power of the high pressurecompressor is reduced so that the gross thermal efficiency is enhanced.Also, the high pressure compressor outlet temperature is reduced so thatreliability of the disc strength of the high pressure compressor outletportion is enhanced. Further, the combustor inlet gas temperature isreduced so that reliability of the high temperature portion of thecombustor is enhanced.

(26) A turbine plant as mentioned in aspect (16) above, characterized inthat the bottoming system comprises a water condensing system and a CO₂compressor having no low pressure turbine therein; the condensed waterfrom the water condensing system is partly led into the inlet of thecompressor as the working fluid and the exhaust gas from the hightemperature turbine after being heat-exchanged at the heat exchanger isled into the water condensing system.

In the invention of aspect (26), in addition to the effect of theinvention of aspect (16), the high temperature turbine outlet pressureis reduced and the high temperature turbine outlet temperature isreduced so that the anti-creep life of the final stage moving blade ofthe high temperature turbine can be elongated. Also, the low pressureturbine is eliminated so that the construction cost is reduced. Further,the compressor inlet temperature is reduced and the power of thecompressor is reduced so that the gross thermal efficiency is enhanced.

(27) A turbine plant as mentioned in aspect (26) above, characterized inthat the compressor comprises a low pressure compressor and a highpressure compressor. Between the low pressure compressor and the highpressure compressor, a passage is provided for flowing therethrough theworking fluid via an intercooler, and a portion of the condensed waterfrom the bottoming system is mixed into the intercooler under pressure.

In the invention of aspect (27), in addition to the effect of theinvention of aspect (26), the low pressure compressor outlet gas istemperature-reduced and the compression power of the high pressurecompressor is reduced so that the gross thermal efficiency is enhanced.Also, the high pressure compressor outlet temperature is reduced so thatreliability of the disc strength of the high pressure compressor outletportion is enhanced. Further, the combustor inlet gas temperature isreduced so that reliability of the high temperature portion of thecombustor is enhanced.

As a summary of the effects obtained by the present invention describedabove in (1) to aspect (27), as compared with the prior art turbineplant, the herebelow mentioned remarkable effects can be obtained:enhancement of the gross thermal efficiency, enhancement of thereliability of the high temperature turbine by cooling of the hightemperature turbine, enhancement of the reliability of the combustorhigh temperature portion by reduction of the combustor inlet gastemperature, enhancement of the disc strength of the high pressurecompressor outlet portion, and reduction of the construction cost byelimination of the low pressure turbine and/or the high pressureturbine, etc.

Also, the present invention is effective not only for the methanol fuelbut also for other fossil fuels including the surplus gas generated atan iron making plant and the coal gasified fuel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of a turbine plant of a first embodimentaccording to the present invention.

FIG. 2 is a diagrammatic view of a turbine plant of a second embodimentaccording to the present invention.

FIG. 3 is a diagrammatic view of a turbine plant of a third embodimentaccording to the present invention.

FIG. 4 is a diagrammatic view of a turbine plant of a fourth embodimentaccording to the present invention.

FIG. 5 is a diagrammatic view of a turbine plant of a fifth embodimentaccording to the present invention.

FIG. 6 is a diagrammatic view of a turbine plant of a sixth embodimentaccording to the present invention.

FIG. 7 is a diagrammatic view of a turbine plant of a seventh embodimentaccording to the present invention.

FIG. 8 is a diagrammatic view of a turbine plant of an eighth embodimentaccording to the present invention.

FIG. 9 is a diagrammatic view of a turbine plant of a ninth embodimentaccording to the present invention.

FIG. 10 is a diagrammatic view of a turbine plant of a tenth embodimentaccording to the present invention.

FIG. 11 is a diagrammatic view of a turbine plant of an eleventhembodiment according to the present invention.

FIG. 12 is a diagrammatic view of a turbine plant of a twelfthembodiment according to the present invention.

FIG. 13 is a diagrammatic view of a turbine plant of a thirteenthembodiment according to the present invention.

FIG. 14 is a diagrammatic view of a turbine plant of a fourteenthembodiment according to the present invention.

FIG. 15 is a diagrammatic view of a turbine plant of a fifteenthembodiment according to the present invention.

FIG. 16 is a diagrammatic view of a turbine plant of a sixteenthembodiment according to the present invention.

FIG. 17 is a diagrammatic view of a turbine plant of a seventeenthembodiment according to the present invention.

FIG. 18 is a diagrammatic view of a turbine plant of an eighteenthembodiment according to the present invention.

FIG. 19 is a diagrammatic view of a turbine plant of a nineteenthembodiment according to the present invention.

FIG. 20 is a diagrammatic view of a turbine plant of a twentiethembodiment according to the present invention.

FIG. 21 is a diagrammatic view of a turbine plant of a twenty-firstembodiment according to the present invention.

FIG. 22 is a diagrammatic view of a turbine plant of a twenty-secondembodiment according to the present invention.

FIG. 23 is a diagrammatic view of a turbine plant of a twenty-thirdembodiment according to the present invention.

FIG. 24 is a diagrammatic view of a turbine plant of a twenty-fourthembodiment according to the present invention.

FIG. 25 is a diagrammatic view of a turbine plant of a twenty-fifthembodiment according to the present invention.

FIG. 26 is a diagrammatic view of a turbine plant of a twenty-sixthembodiment according to the present invention.

FIG. 27 is a diagrammatic view of a turbine plant of a twenty-seventhembodiment according to the present invention.

FIG. 28 is a diagrammatic view of a turbine plant in the prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Herebelow, embodiments according to the present invention will bedescribed concretely with reference to figures. FIG. 1 is a diagrammaticview of a turbine plant of a first embodiment according to the presentinvention, wherein a turbine plant using a methanol fuel is shown. Theturbine plant using the methanol fuel of the present embodimentcomprises a reformer 13 in addition to the system in the prior art shownin FIG. 28, and the methanol fuel is supplied into the combustor 2 viathe reformer 13.

In the reformer 13, a mixture of the methanol (CH₃OH) as fuel and water(H₂O) can be reformed into hydrogen (H₂O) and carbon dioxide (CO₂) byheat of absorption Q at the reformer 13, wherein the following reactionformula takes place in the reformer 13:

CH₃₀OH+H₂O+Q→H₂+CO₂

In this reaction formula, the heat of absorption Q is given by heatexchange at the reformer 13. Thereby, the same effect is obtained asthat of a fuel heating system in which fuel is heated so that fuel flowrate thereof is reduced and gross thermal efficiency thereof is enhancedin a gas turbine using an ordinary natural gas as fuel. Hence, by thereforming, the gross thermal efficiency can be enhanced.

Also, in the combustor 2, a mixture gas of the hydrogen (H₂) and carbondioxide generated by the reforming process reacts on oxygen which isnecessary for an equivalent combustion of the hydrogen to become a hightemperature mixture gas of steam (H₂O) and carbon dioxide (CO₂). Thisreaction is as follows, wherein working fluid is the same as that of theprior art shown in FIG. 28:

H₂+CO₂+½O₂→H₂O+CO₂

Further, in order to cool a high temperature portion of the hightemperature turbine 3, cooling medium 14 (mixture gas of steam andcarbon dioxide) used for cooling the high temperature turbine 3 isextracted from an outlet of the high pressure turbine 6 and from anoutlet of the compressor 1. Construction of other portions is the sameas that of the prior art shown in FIG. 28.

According to the present first embodiment, the reformer 13 can reformthe mixture of methanol (CH₃OH) as fuel and water (H₂O) into hydrogen(H₂) and carbon dioxide (CO₂) by the heat of absorption Q there. Theheat of absorption Q at the reformer 13 has the same effect as the fuelheating system in which fuel is heated so that fuel flow rate thereof isreduced and the gross thermal efficiency is thereby enhanced in a gasturbine using ordinary natural gas as fuel. Hence, the effect to enhancethe gross thermal efficiency can be obtained.

Also, the cooling medium 14 (mixture gas of steam and carbon dioxide) isextracted from the outlet of the high pressure turbine 6 and the outletof the compressor 1 so that so as to cool the high temperature portionof the high temperature turbine 3 and to enhance the reliability of thehigh temperature turbine 3.

FIG. 2 is a diagrammatic view of a turbine plant of a second embodimentaccording to the present invention. In the second embodiment shownthere, the compressor 1 of the first embodiment shown in FIG. 1 isdivided into a low pressure compressor 1 a and a high pressurecompressor 1 b, and an intercooler 15 is provided therebetween. Otherportions of the system are the same as that shown in FIG. 1 withdescription thereof being omitted.

In this intercooler 15, a low pressure compressor 1 a outlet gas (a highpressure compressor 1 b inlet gas) is mixed with the pressurized waterwhich has been pressurized approximately to a low pressure compressor 1a outlet pressure by the pressure pump 10 to be temperature-reduced sothat a compression power of the high pressure compressor 1 b is reducedand a high pressure compressor 1 b outlet temperature is reduced. Thus,reliability of a disc strength of a high pressure compressor 1 b outletportion is enhanced, and because a combustor 2 inlet gas temperature isbeing reduced, reliability of the high temperature portion of thecombustor 2 can be enhanced.

According to the present second embodiment, the low pressure compressor1 a outlet gas (the high pressure compressor 1 b inlet gas) istemperature-reduced. Thus, the compression power of the high pressurecompressor 1 b can be reduced and the gross thermal efficiency can beenhanced. Also, the high pressure compressor 1 b outlet temperature isreduced so that reliability of the disc strength of the high pressurecompressor 1 b outlet portion can be enhanced. Further, the combustor 2inlet gas temperature is reduced so as to enhance the reliability of thehigh temperature portion of the combustor 2. Other effects of the secondembodiment are the same as that of the first embodiment.

FIG. 3 is a diagrammatic view of a turbine plant of a third embodimentaccording to the present invention. In the present third embodiment, ascompared with the first embodiment shown in FIG. 1, a regenerative heatexchanger 16 is provided on a downstream side of the high temperatureturbine 3 so that a compressor 1 outlet gas is heat-exchanged with ahigh temperature turbine 3 exhaust gas. Thus, a combustor 2 inlet gastemperature is elevated, fuel flow rate is reduced and the gross thermalefficiency is enhanced. Construction of other portions is the same asthat shown in FIG. 1 with description thereof being omitted.

According to the present third embodiment, by the regenerative heatexchanger 16 being provided, the combustor 2 inlet gas temperature iselevated more than in the first embodiment of FIG. 1, the fuel flow rateis reduced further and the further enhancement of the gross thermalefficiency can be obtained. Other effects of the third embodiment arethe same as that of the first embodiment.

FIG. 4 is a diagrammatic view of a turbine plant of a fourth embodimentaccording to the present invention. In the present fourth embodiment,the compressor 1 of the third embodiment shown in FIG. 3 is divided intoa low pressure compressor 1 a and a high pressure compressor 1 b, and anintercooler 15 is provided therebetween.

In this intercooler 15, a low pressure compressor 1 a outlet gas (a highpressure compressor 1 b inlet gas) is mixed with the pressurized waterwhich has been pressurized approximately to a low pressure compressor 1a outlet pressure by the pressure pump 10 to be temperature-reduced sothat a compression power of the high pressure compressor 1 b is reducedand a high pressure compressor 1 b outlet temperature is reduced. Thus,reliability of a disc strength of a high pressure compressor 1 b outletportion is enhanced and also, because a combustor 2 inlet gastemperature is reduced, reliability of the high temperature portion ofthe combustor 2 can be enhanced. Construction of other portions is thesame as that of the third embodiment with description thereof beingomitted.

According to the present fourth embodiment, as mentioned above, theeffects are to reduce the low pressure compressor 1 a outlet gastemperature, to reduce the compression power of the high pressurecompressor 1 b and to enhance the gross thermal efficiency. Also,reduction of the high pressure compressor 1 b outlet temperature andenhancement of the reliability of the disc strength of the high pressurecompressor 1 b outlet portion can be obtained. Further, the effect toenhance the reliability of the high temperature portion of the combustor2 can be obtained. Other effects of the fourth embodiment are the sameas that of the third embodiment.

FIG. 5 is a diagrammatic view of a turbine plant of a fifth embodimentaccording to the present invention. In the present fifth embodiment, thehigh pressure turbine 6 of the first embodiment shown in FIG. 1 iseliminated so that construction cost thereof is reduced. Thereby, thehigh temperature turbine cooling medium 14 which has been extracted fromthe high pressure turbine 6 outlet in the first embodiment becomes hightemperature. Hence, a modification in the construction is added so thatthe cooling medium 14 is extracted from a high temperature gas side ofthe heat exchangers 4, 5. Construction of other portions is the same asthat shown in FIG. 1 with a description thereof being omitted.

According to the present fifth embodiment, the high pressure turbine 6of the first embodiment shown in FIG. 1 is eliminated so that reductionof the construction cost can be obtained. Other effects of the fifthembodiment are the same as that of the first embodiment.

FIG. 6 is a diagrammatic view of a turbine plant of a sixth embodimentaccording to the present invention. In the present sixth embodiment, thecompressor 1 of the fifth embodiment shown in FIG. 5 is divided into alow pressure compressor 1 a and a high pressure compressor 1 b, and anintercooler 15 is provided therebetween. In this intercooler 15, a lowpressure compressor 1 a outlet gas (a high pressure compressor 1 b inletgas) is mixed with the pressurized water which has been pressurizedapproximately to a low pressure compressor 1 a outlet pressure by thepressure pump 10 to be temperature-reduced so that a compression powerof the high pressure compressor 1 b is reduced and a high pressurecompressor 1 b outlet temperature is reduced. Thus, reliability of adisc strength of a high pressure compressor 1 b outlet portion isenhanced, and because combustor 2 inlet gas temperature is beingreduced, reliability of the high temperature portion of the combustor 2can be enhanced. Construction of other portions is the same as that ofthe fifth embodiment with description thereof being omitted.

According to the present sixth embodiment, as mentioned above, theeffects are to reduce the low pressure compressor 1 a outlet gastemperature, to reduce the compression power of the high pressurecompressor 1 b and to enhance the gross thermal efficiency. Also, thereduction of the high pressure compressor 1 b outlet temperature and theenhancement of the reliability of the disc strength of the high pressurecompressor 1 b outlet portion can be obtained. Further, the enhancementof the reliability of the high temperature portion of the combustor 2can be obtained. Other effects of the sixth embodiment are the same asthat of the fifth embodiment.

FIG. 7 is a diagrammatic view of a turbine plant of a seventh embodimentaccording to the present invention. In the present seventh embodiment,as compared with the first embodiment shown in FIG. 1, the high pressureturbine 6, and the low pressure turbine 7 and CO₂ compressor 8 withmotor 11 of the bottoming system are eliminated so that constructioncost thereof is reduced. Thereby, the high temperature turbine coolingmedium 14 which has been extracted from the high pressure turbine 6outlet in the first embodiment becomes high temperature. Hence, amodification in the construction is added so that the cooling medium 14is extracted from a high temperature gas side of the heat exchangers 4,5. Also, a supply system to the condenser 9 is modified so that supplytherefor is done from a heat exchanger 5 outlet. Thus, a supply line tothe compressor 1 is modified so that supply therefor is done from acondenser 9 outlet. Construction of other portions are the same as thatof the first embodiment shown in FIG. 1.

According to the present seventh embodiment, the high pressure turbineand the bottoming system are eliminated so as to reduce the constructioncost. Also, the effect of reducing the compressor 1 inlet temperature,reducing the power of the compressor 1 and to enhance the gross thermalefficiency can be obtained. Other effect of the seventh embodiment issame as that of the first embodiment shown in FIG. 1.

FIG. 8 is a diagrammatic view of a turbine plant of an eighth embodimentaccording to the present invention. In the present eighth embodiment,the compressor 1 of the seventh embodiment shown in FIG. 7 is dividedinto a low pressure compressor 1 a and a high pressure compressor 1 b,and an intercooler 15 is provided therebetween. In this intercooler 15,a low pressure compressor 1 a outlet gas (a high pressure compressor 1 binlet gas) is mixed with the pressurized water which has beenpressurized approximately to a low pressure compressor 1 a outletpressure by the pressure pump 10 to be temperature-reduced so that acompression power of the high pressure compressor 1 b is reduced and ahigh pressure compressor 1 b outlet temperature is reduced. Thus,reliability of a disc strength of a high pressure compressor 1 b outletportion is enhanced, and because a combustor 2 inlet gas temperature isreduced, reliability of the high temperature portion of the combustor 2can be enhanced. Construction of other portions are the same as that ofthe seventh embodiment with description thereof being omitted.

According to the present eighth embodiment, as mentioned above, theeffects are to reduce the low pressure compressor 1 a outlet gastemperature, to reduce the compression power of the high pressurecompressor 1 b and to enhance the gross thermal efficiency. Also,reduction of the high pressure compressor 1 b outlet temperature and theenhancement of the reliability of the disc strength of the high pressurecompressor 1 b outlet portion can be obtained. Further, the effect toenhance the reliability of the high temperature portion of the combustor2 can be obtained. Other effects of the eighth embodiment are the sameas that of the seventh embodiment.

FIG. 9 is a diagrammatic view of a turbine plant of a ninth embodimentaccording to the present invention. In the present ninth embodiment, ascompared with the third embodiment shown in FIG. 3, the low pressureturbine 7 and CO₂ compressor 8 with motor 11 of the bottoming system areeliminated so that construction cost thereof is reduced. Thereby, asupply system to the condenser 9 is modified so that supply therefor isprovided from a heat exchanger 5 outlet. Thus, a supply line to thecompressor 1 is modified so that supply therefor is provided from acondenser 9 outlet. Construction of other portions is the same as thatof the third embodiment shown in FIG. 3.

According to the present ninth embodiment, the low pressure turbine 7and the CO₂ compressor 8 with motor 11 of the bottoming system in thethird embodiment are eliminated so that the reduction of theconstruction cost can be obtained. Also, the effect of reducing thecompressor 1 inlet gas temperature, reducing the power of the compressor1 and enhancing the gross thermal efficiency can be obtained. Othereffects of the ninth embodiment are the same as that of the thirdembodiment shown in FIG. 3.

FIG. 10 is a diagrammatic view of a turbine plant of a tenth embodimentaccording to the present invention. In the present tenth embodiment, thecompressor 1 of the ninth embodiment shown in FIG. 9 is divided into alow pressure compressor 1 a and a high pressure compressor 1 b, and anintercooler 15 is provided therebetween. In this intercooler 15, a lowpressure compressor 1 a outlet gas (a high pressure compressor 1 b inletgas) is mixed with the pressurized water which has been pressurizedapproximately to a low pressure compressor 1 a outlet pressure by thepressure pump 10 to be temperature-reduced so that a compression powerof the high pressure compressor 1 b is reduced and a high pressurecompressor 1 b outlet temperature is reduced. Thus, reliability of adisc strength of a high pressure compressor 1 b outlet portion isenhanced, and because a combustor 2 inlet gas temperature is reduced,reliability of the high temperature portion of the combustor 2 can beenhanced. Construction of other portions is the same as that of theninth embodiment with description thereof being omitted.

According to the present tenth embodiment, as mentioned above, theeffects are to reduce the low pressure compressor 1 a outlet gastemperature, to reduce the compression power of the high pressurecompressor 1 b and to enhance the gross thermal efficiency. Also, thereduction of the high pressure compressor 1 b outlet temperature and theenhancement of the reliability of the disc strength of the high pressurecompressor 1 b outlet portion can be obtained. Further, the enhancementof the reliability of the high temperature portion of the combustor 2can be obtained. Other effects of the tenth embodiment are the same asthat of the ninth embodiment.

FIG. 11 is a diagrammatic view of a turbine plant of an eleventhembodiment according to the present invention. In the present eleventhembodiment, as compared with the first embodiment shown in FIG. 1,outlet pressure of the high temperature turbine 3 is reduced and outlettemperature of the high temperature turbine 3 is also reduced. Thus,anti-creep life of a final stage moving blade of the high temperatureturbine 3 is elongated. Also, the high pressure turbine 6 and the lowpressure turbine 7 are eliminated so that construction cost thereof isreduced. Further, a supply system to the condenser 9 is modified so thatsupply therefor is provided from a heat exchanger 5 outlet. Thus, asupply line to the compressor 1 is modified so that supply therefor isprovided from a condenser 9 outlet. Construction of other portions isthe same as that of the first embodiment shown in FIG. 1.

According to the present eleventh embodiment, as mentioned above, anelongation of the anti-creep life of the final stage moving blade of thehigh temperature turbine 3 to a greater extent than the first embodimentcan be obtained. Also, the high pressure turbine 6 and the low pressureturbine 7 are eliminated, so a reduction in the construction cost can beobtained. Further, a reduction in the compressor 1 inlet gastemperature, a reduction in the power of the compressor 1 and anenhancement in the gross thermal efficiency can be obtained. Othereffects of the eleventh embodiment are the same as that of the firstembodiment.

FIG. 12 is a diagrammatic view of a turbine plant of a twelfthembodiment according to the present invention. In the present twelfthembodiment, the compressor 1 of the eleventh embodiment shown in FIG. 11is divided into a low pressure compressor 1 a and a high pressurecompressor 1 b, and an intercooler 15 is provided therebetween. In thisintercooler 15, a low pressure compressor 1 a outlet gas (a highpressure compressor 1 b, inlet gas) is mixed with the pressurized waterwhich has been pressurized approximately to a low pressure compressor 1a outlet pressure by the pressure pump 10 to be temperature-reduced sothat a compression power of the high pressure compressor 1 b is reducedand a high pressure compressor 1 b outlet temperature is reduced. Thus,reliability of a disc strength of a high pressure compressor 1 b outletportion is enhanced, and because a combustor 2 inlet gas temperature isreduced, reliability of the high temperature portion of the combustor 2can be enhanced. Construction of other portions is the same as that ofthe eleventh embodiment with description thereof being omitted.

According to the present twelfth embodiment, as mentioned above, theeffects are to reduce the low pressure compressor 1 a outlet gastemperature, to reduce the compression power of the high pressurecompressor 1 b and to enhance the gross thermal efficiency. Also, areduction in the high pressure compressor 1 b outlet temperature andenhancement of the reliability of the disc strength of the high pressurecompressor 1 b outlet portion can be obtained. Further, an enhancementof the reliability of the high temperature portion of the combustor 2can be obtained. Other effects of the twelfth embodiment are the same asthat of the eleventh embodiment.

FIG. 13 is a diagrammatic view of a turbine plant of a thirteenthembodiment according to the present invention. In the present thirteenthembodiment, as compared with the third embodiment shown in FIG. 3, theoutlet pressure of the high temperature turbine 3 is reduced and theoutlet temperature of the high temperature turbine 3 is also reduced.Therefore, anti-creep life of a final stage moving blade of the hightemperature turbine 3 is elongated. Also, the low pressure turbine 7 iseliminated so that construction cost thereof is reduced. Further, asupply system to the condenser 9 is modified so that supply therefor isprovided from a heat exchanger 5 outlet. Thus, a supply line to thecompressor 1 is modified so that supply therefor is provided from acondenser 9 outlet. Construction of other portions is the same as thatof the third embodiment shown in FIG. 3.

According to the present thirteenth embodiment, as mentioned above, theelongation of the anti-creep life of the final stage moving blade of thehigh temperature turbine 3 can be obtained. Also, the low pressureturbine 7 is eliminated, so a reduction in the construction cost can beobtained. Further, a reduction in the compressor 1 inlet gastemperature, a reduction in the power of the compressor 1 and anenhancement in the gross thermal efficiency can be obtained. Othereffects of the thirteenth embodiment are the same as that of the thirdembodiment.

FIG. 14 is a diagrammatic view of a turbine plant of a fourteenthembodiment according to the present invention. In the present fourteenthembodiment, the compressor 1 of the thirteenth embodiment shown in FIG.13 is divided into a low pressure compressor 1 a and a high pressurecompressor 1 b, and an intercooler 15 is provided therebetween. In thisintercooler 15, a low pressure compressor 1 a outlet gas (a highpressure compressor 1 b inlet gas) is mixed with the pressurized waterwhich has been pressurized approximately to a low pressure compressor 1a outlet pressure by the pressure pump 10 to be temperature-reduced sothat a compression power of the high pressure compressor 1 b is reducedand a high pressure compressor 1 b outlet temperature is reduced. Thus,reliability of a disc strength of a high pressure compressor 1 b outletportion is enhanced, and because a combustor 2 inlet gas temperature isreduced, reliability of the high temperature portion of the combustor 2can be enhanced. Construction of other portions is the same as that ofthe thirteenth embodiment with description thereof being omitted.

According to the present fourteenth embodiment, as mentioned above, theeffects are to reduce the low pressure compressor 1 a outlet gastemperature, to reduce the compression power of the high pressurecompressor 1 b and to enhance the gross thermal efficiency. Also, areduction in the high pressure compressor 1 b outlet temperature and anenhancement of the reliability of the disc strength of the high pressurecompressor 1 b outlet portion can be obtained. Further, an enhancementof the reliability of the high temperature portion of the combustor 2can be obtained. Other effects of the fourteenth embodiment are the sameas that of the thirteenth embodiment.

FIG. 15 is a diagrammatic view of a turbine plant of a fifteenthembodiment according to the present invention. In the present fifteenthembodiment, which uses methanol as fuel, an intercooler 15 is added tothe prior art example shown in FIG. 28. That is, the compressor 1 of theprior art example shown in FIG. 28 is divided into a low pressurecompressor 1 a and a high pressure compressor 1 b, and an intercooler 15is provided therebetween. In this intercooler 15, a low pressurecompressor 1 a outlet gas (a high pressure compressor 1 b inlet gas) ismixed with the pressurized water which has been pressurizedapproximately to a low pressure compressor 1 a outlet pressure by thepressure pump 10 to be temperature-reduced so that a compression powerof the high pressure compressor 1 b is reduced and a gross thermalefficiency is enhanced. Also, a high pressure compressor 1 b outlettemperature is reduced so that reliability of a disc strength of a highpressure compressor 1 b outlet portion is enhanced, and because acombustor 2 inlet gas temperature is reduced, reliability of the hightemperature portion of the combustor 2 can be enhanced.

Also, in the combustor 2, methanol (CH₃OH) reacts on the oxygen (O₂)which is needed for an equivalent combustion to generate a hightemperature mixture gas of steam (H₂O) and carbon dioxide (CO₂) by thefollowing reaction formula:

CH₃OH+O₂→CO₂+2H₂O+heat

Accordingly, the working fluid in this plant is carbon dioxide (CO₂) andsteam (H₂O), like in the prior art case shown in FIG. 28.

Also, in order to cool the high temperature portion of the hightemperature turbine 3, cooling medium 14 (mixture gas of steam andcarbon dioxide) is extracted from an outlet of the high pressure turbine6 and an outlet of the compressor 1.

It is to be noted that although methanol as fuel has been describedhere, it is also possible to use other fossil fuels. Further, it is alsoeffective to use a fuel of a surplus gas generated at an iron makingplant or the like, a coal gasified fuel, etc.

According to the present fifteenth embodiment, as mentioned above, theeffects are to reduce the low pressure compressor 1 a outlet gastemperature, to reduce the compression power of the high pressurecompressor 1 b and to enhance the gross thermal efficiency. Also, areduction in the high pressure compressor 1 b outlet temperature and anenhancement in the reliability of the disc strength of the high pressurecompressor 1 b outlet portion can be obtained.

Further, the combustor 2 inlet gas temperature is reduced, soenhancement of the reliability of the high temperature portion of thecombustor 2 can be obtained. Also, the cooling medium 14 (mixture gas ofsteam and carbon dioxide) is extracted from the high pressure turbine 6outlet and the compressor 1 outlet, so cooling of the high temperatureportion of the high temperature turbine 3 and enhancement of thereliability of the high temperature turbine 3 can be obtained.

FIG. 16 is a diagrammatic view of a turbine plant of a sixteenthembodiment according to the present invention. In the present sixteenthembodiment, a regenerative heat exchanger 16 is provided on a downstreamside of the high temperature turbine 3 so that a compressor 1 outlet gasis heat-exchanged with a high temperature turbine 3 exhaust gas. Thus, acombustor 2 inlet gas temperature is elevated, fuel flow rate is reducedand the gross thermal efficiency is enhanced.

Also, in order to cool the high temperature portion of the hightemperature turbine 3, like in the fifteenth embodiment, cooling medium14 (mixture gas of steam and carbon dioxide) is extracted from an outletof the high pressure turbine 6 and an outlet of the compressor 1.Construction of other portions is the same as that of the prior artexample shown in FIG. 28.

According to the present sixteenth embodiment, the combustor 2 inlet gastemperature is elevated and the fuel flow rate is reduced, soenhancement of the gross thermal efficiency can be obtained. Also, thecooling medium (mixture gas of steam and carbon dioxide) is extractedfrom the high pressure turbine 6 and the compressor 1 outlet, so coolingof the high temperature portion of the high temperature turbine 3 andenhancement of the reliability of the high temperature turbine 3 can beobtained.

FIG. 17 is a diagrammatic view of a turbine plant of a seventeenthembodiment according to the present invention. In the presentseventeenth embodiment, the compressor 1 of the sixteenth embodimentshown in FIG. 16 is divided into a low pressure compressor 1 a and ahigh pressure compressor 1 b, and an intercooler 15 is providedtherebetween. In this intercooler 15, a low pressure compressor 1 aoutlet gas (a high pressure compressor 1 b inlet gas) is mixed with thepressurized water which has been pressurized approximately to a lowpressure compressor 1 a outlet pressure by the pressure pump 10 to betemperature-reduced so that a compression power of the high pressurecompressor 1 b is reduced and a high pressure compressor 1 b outlettemperature is reduced. Thus, reliability of a disc strength of a highpressure compressor 1 b outlet portion is enhanced, and because acombustor 2 inlet gas temperature is reduced, reliability of the hightemperature portion of the combustor 2 can be enhanced. Construction ofother portions is the same as that of the sixteenth embodiment withdescription thereof being omitted.

According to the present sixth embodiment, as mentioned above, theeffects are to reduce the low pressure compressor 1 a outlet gastemperature, to reduce the compression power of the high pressurecompressor 1 b and to enhance the gross thermal efficiency. Also, areduction in the high pressure compressor 1 b outlet temperature and anenhancement in the reliability of the disc strength of the high pressurecompressor 1 b outlet portion can be obtained. Further, enhancement ofthe reliability of the high temperature portion of the combustor 2 canbe obtained. Other effects of the seventeenth embodiment are the same asthat of the sixteenth embodiment.

FIG. 18 is a diagrammatic view of a turbine plant of an eighteenthembodiment according to the present invention. In the present eighteenthembodiment, as compared with the prior art example shown in FIG. 28, thehigh pressure turbine 6 is eliminated, so that construction cost thereofcan be reduced. Also, in order to cool the high temperature portion ofthe high temperature turbine 3, the cooling medium is extracted from thecompressor 1 outlet and from the high temperature gas side between heatexchangers 4, 5 so that reliability of the high temperature turbine 3 isenhanced. Construction of other portions is the same as that of theprior art example shown in FIG. 28.

According to the present eighteenth embodiment, as mentioned above, thereduction in the construction cost can be obtained. Also, because thecooling medium is extracted from the compressor 1 outlet and from thehigh temperature side gas between the heat exchangers 4, 5 to be usedfor cooling of the high temperature portion of the high temperatureturbine 3, enhancement the reliability of the high temperature turbine 3can be obtained.

FIG. 19 is a diagrammatic view of a turbine plant of a nineteenthembodiment according to the present invention. In the present nineteenthembodiment, the compressor 1 of the eighteenth embodiment shown in FIG.18 is divided into a low pressure compressor 1 a and a high pressurecompressor 1 b, and an intercooler 15 is provided therebetween. In thisintercooler 15, a low pressure compressor 1 a outlet gas (a highpressure compressor 1 b inlet gas) is mixed with the pressurized waterwhich has been pressurized approximately to a low pressure compressor 1a outlet pressure by the pressure pump 10 to be temperature-reduced sothat a compression power of the high pressure compressor 1 b is reducedand a high pressure compressor 1 b outlet temperature is reduced. Thus,reliability of a disc strength of a high pressure compressor 1 b outletportion is enhanced, and because a combustor 2 inlet gas temperature isbeing reduced, reliability of the high temperature portion of thecombustor 2 can be enhanced. Construction of other portions is the sameas that of the eighteenth embodiment with description thereof beingomitted.

According to the present nineteenth embodiment, as mentioned above, theeffects are to reduce the low pressure compressor 1 a outlet gastemperature, to reduce the compression power of the high pressurecompressor 1 b and to enhance the gross thermal efficiency. Also,reduction in the high pressure compressor 1 b outlet temperature andenhancement of the reliability of the disc strength of the high pressurecompressor 1 b outlet portion can be obtained. Further, enhancement ofthe reliability of the high temperature portion of the combustor 2 canbe obtained. Other effects of the nineteenth embodiment are the same asthat of the eighteenth embodiment.

FIG. 20 is a diagrammatic view of a turbine plant of a twentiethembodiment according to the present invention. In the present twentiethembodiment, as compared with the prior art example shown in FIG. 28, thehigh pressure turbine 6, and the low pressure turbine 7 and CO₂compressor 8 with motor 11 of the bottoming system are eliminated sothat construction cost thereof is reduced. Thereby, the high temperatureturbine cooling gas which has been extracted from the high pressureturbine 6 outlet in the prior art example of FIG. 28 is extracted from ahigh temperature side gas of the heat exchangers 4, 5, as there is nohigh pressure turbine 6. Also, a supply system to the condenser 9 ismodified so that supply therefor is provided from a heat exchanger 5outlet. Thus, a supply line to the compressor 1 is modified so thatsupply therefor is provided from a condenser 9 outlet. Construction ofother portions is the same as that of the prior art example shown inFIG. 28.

According to the present twentieth embodiment, the high pressure turbineand the bottoming system are eliminated so that reduction in theconstruction cost can be obtained. Also, a reduction in the compressor 1inlet temperature, a reduction in the power of the compressor 1 andenhancement of the gross thermal efficiency can be obtained.

FIG. 21 is a diagrammatic view of a turbine plant of a twenty-firstembodiment according to the present invention. In the presenttwenty-first embodiment, the compressor 1 of the twentieth embodimentshown in FIG. 20 is divided into a low pressure compressor 1 a and ahigh pressure compressor 1 b, and an intercooler 15 is providedtherebetween. In this intercooler 15, a low pressure compressor 1 aoutlet gas (a high pressure compressor 1 b inlet gas) is mixed with thepressurized water which has been pressurized approximately to a lowpressure compressor 1 a outlet pressure by the pressure pump 10 to betemperature-reduced so that a compression power of the high pressurecompressor 1 b is reduced and a high pressure compressor 1 b outlettemperature is reduced. Thus, reliability of a disc strength of a highpressure compressor 1 b outlet portion is enhanced, and because acombustor 2 inlet gas temperature is reduced, reliability of the hightemperature portion of the combustor 2 can be enhanced. Construction ofother portions is the same as that of the twentieth embodiment withdescription thereof being omitted.

According to the present twenty-first embodiment, as mentioned above,the effects are to reduce the low pressure compressor 1 a outlet gastemperature, to reduce the compression power of the high pressurecompressor 1 b and to enhance the gross thermal efficiency. Also, areduction in the high pressure compressor 1 b outlet temperature andenhancement of the reliability of the disc strength of the high pressurecompressor 1 b outlet portion can be obtained. Further, enhancement ofthe reliability of the high temperature portion of the combustor 2 canbe obtained. Other effects of the twenty-first embodiment are the sameas that of the twentieth embodiment.

FIG. 22 is a diagrammatic view of a turbine plant of a twenty-secondembodiment according to the present invention. In the presenttwenty-second embodiment, as compared with the sixteenth embodimentshown in FIG. 16, the low pressure turbine 7 and CO₂ compressor 8 withmotor 11 of the bottoming system are eliminated so that constructioncost thereof is reduced. Also, a supply system to the condenser 9 ismodified so that supply therefor is provided from a heat exchanger 5outlet. Thus, a supply line to the compressor 1 is modified so thatsupply therefor is provided from a condenser 9 outlet.

According to the present twenty-second embodiment, the bottoming systemis eliminated so that a reduction in the construction cost can beobtained. Also, a reduction in the compressor 1 inlet temperature,reduction in the power of the compressor 1 and enhancement of the grossthermal efficiency can be obtained. Other effects of the twenty-secondembodiment are the same as that of the sixteenth embodiment shown inFIG. 16.

FIG. 23 is a diagrammatic view of a turbine plant of a twenty-thirdembodiment according to the present invention. In the presenttwenty-third embodiment, the compressor 1 of the twenty-secondembodiment shown in FIG. 22 is divided into a low pressure compressor 1a and a high pressure compressor 1 b, and an intercooler 15 is providedtherebetween. In this intercooler 15, a low pressure compressor 1 aoutlet gas (a high pressure compressor 1 b inlet gas) is mixed with thepressurized water which has been pressurized approximately to a lowpressure compressor 1 a outlet pressure by the pressure pump 10 to betemperature-reduced so that a compression power of the high pressurecompressor 1 b is reduced and a high pressure compressor 1 b outlettemperature is reduced. Thus, reliability of a disc strength of a highpressure compressor 1 b outlet portion is enhanced, and because acombustor 2 inlet gas temperature is reduced, reliability of the hightemperature portion of the combustor 2 can be enhanced. Construction ofother portions is the same as that of the twenty-second embodiment withdescription thereof being omitted.

According to the present twenty-third embodiment, as mentioned above,the effects are to reduce the low pressure compressor 1 a outlet gastemperature, to reduce the compression power of the high pressurecompressor 1 b and to enhance the gross thermal efficiency. Also, thereduction in the high pressure compressor 1 b outlet temperature andenhancement of the reliability of the disc strength of the high pressurecompressor 1 b outlet portion can be obtained. Further, enhancement ofthe reliability of the high temperature portion of the combustor 2 canbe obtained. Other effects of the twenty-third embodiment are the sameas that of the twenty-second embodiment.

FIG. 24 is a diagrammatic view of a turbine plant of a twenty-fourthembodiment according to the present invention. In the presenttwenty-fourth embodiment, as compared with the prior art example shownin FIG. 28, the outlet pressure of the high temperature turbine 3 isreduced and the outlet temperature of the high temperature turbine 3 isalso reduced so that anti-creep life of a final stage moving blade ofthe high temperature turbine 3 is elongated. Also, the high pressureturbine 6 and the low pressure turbine 7 are eliminated so thatconstruction cost thereof is reduced. Also, in order to cool the hightemperature portion of the high temperature turbine 3, cooling medium isextracted from an outlet of the compressor 1 and from a high temperaturegas side between heat exchangers 4, 5 so that reliability of the hightemperature turbine 3 is enhanced. Further, a supply system to thecondenser 9 is modified so that supply therefor is provided from a heatexchanger 5 outlet. Thus, a supply line to the compressor 1 is modifiedso that supply therefor is provided from a condenser 9 outlet.Construction of other portions is the same as that of the prior artexample shown in FIG. 28.

According to the present twenty-fourth embodiment, as mentioned above,elongation of the anti-creep life of the final stage moving blade of thehigh temperature turbine 3 can be obtained. Also, a reduction in theconstruction cost can be obtained. Further, the high temperature portionof the high temperature turbine 3 is cooled, so that enhancement of thereliability of the high temperature turbine 3 can be obtained. Stillfurther, a reduction in the compressor 1 inlet gas temperature, areduction in the power of the compressor 1 and to enhancement of thegross thermal efficiency can be obtained.

FIG. 25 is a diagrammatic view of a turbine plant of a twenty-fifthembodiment according to the present invention. In the presenttwenty-fifth embodiment, the compressor 1 of the twenty-fourthembodiment shown in FIG. 24 is divided into a low pressure compressor 1a and a high pressure compressor 1 b, and an intercooler 15 is providedtherebetween. In this intercooler 15, a low pressure compressor 1 aoutlet gas (a high pressure compressor 1 b inlet gas) is mixed with thepressurized water which has been pressurized approximately to a lowpressure compressor 1 a outlet pressure by the pressure pump 10 to betemperature-reduced so that a compression power of the high pressurecompressor 1 b is reduced and a high pressure compressor 1 b outlettemperature is reduced. Thus, reliability of a disc strength of a highpressure compressor 1 b outlet portion is enhanced, and because acombustor 2 inlet gas temperature is reduced, reliability of the hightemperature portion of the combustor 2 can be enhanced. Construction ofother portions is the same as that of the fifth embodiment withdescription thereof being omitted.

According to the present twenty-fifth embodiment, as mentioned above,the effects are to reduce the low pressure compressor 1 a outlet gastemperature, to reduce the compression power of the high pressurecompressor 1 b and to enhance the gross thermal efficiency. Also, areduction in the high pressure compressor 1 b outlet temperature andenhancement of the reliability of the disc strength of the high pressurecompressor 1 b outlet portion can be obtained. Further, enhancement ofthe reliability of the high temperature portion of the combustor 2 canbe obtained. Other effects of the twenty-fifth embodiment are the sameas that of the twenty-fourth embodiment.

FIG. 26 is a diagrammatic view of a turbine plant of a twenty-sixthembodiment according to the present invention. In the presenttwenty-sixth embodiment, as compared with the sixteenth embodiment shownin FIG. 16, the outlet pressure of the high temperature turbine 3 isreduced and the outlet temperature of the high temperature turbine 3 isalso reduced. Thus, anti-creep life of a final stage moving blade of thehigh temperature turbine 3 is elongated. Also, the low pressure turbine7 is eliminated so that construction cost thereof is reduced. Further, asupply system to the condenser 9 is modified so that supply therefor isprovided from a heat exchanger 5 outlet. Thus, a supply line to thecompressor 1 is modified so that supply therefor is provided from acondenser 9 outlet. Construction of other portions is the same as thatof the sixteenth embodiment shown in FIG. 16.

According to the present twenty-sixth embodiment, as mentioned above, anelongation of the anti-creep life of the final stage moving blade of thehigh temperature turbine 3 can be obtained. Also, the low pressureturbine 7 is eliminated, so a reduction in the construction cost can beobtained. Further, reduction in the compressor 1 inlet gas temperature,a reduction in the power of the compressor 1 and enhancement of thegross thermal efficiency can be obtained.

FIG. 27 is a diagrammatic view of a turbine plant of a twenty-seventhembodiment according to the present invention. In the presenttwenty-seventh embodiment, the compressor 1 of the twenty-sixthembodiment shown in FIG. 26 is divided into a low pressure compressor 1a and a high pressure compressor 1 b, and an intercooler 15 is providedtherebetween. In this intercooler 15, a low pressure compressor 1 aoutlet gas (a high pressure compressor 1 b inlet gas) is mixed with thepressurized water which has been pressurized approximately to a lowpressure compressor 1 a outlet pressure by the pressure pump 10 to betemperature-reduced so that a compression power of the high pressurecompressor 1 b is reduced and a high pressure compressor 1 b outlettemperature is reduced. Thus, reliability of a disc strength of a highpressure compressor 1 b outlet portion is enhanced, and because acombustor 2 inlet gas temperature is reduced, reliability of the hightemperature portion of the combustor 2 can be enhanced. Construction ofother portions is the same as that of the twenty-sixth embodiment withdescription thereof being omitted.

According to the present twenty-seventh embodiment, as mentioned above,the effects are to reduce the low pressure compressor 1 a outlet gastemperature, to reduce the compression power of the high pressurecompressor 1 b and to enhance the gross thermal efficiency. Also, areduction in the high pressure compressor 1 b outlet temperature andenhancement of the reliability of the disc strength of the high pressurecompressor 1 b outlet portion can be obtained. Further, enhancement ofthe reliability of the high temperature portion of the combustor 2 canbe obtained. Other effects of the twenty-seventh embodiment are the sameas that of the twenty-sixth embodiment.

It is understood that the invention is not limited to the particularconstruction and arrangement herein illustrated and described butembraces such modified forms thereof as come within the scope of thefollowing claims.

What is claimed is:
 1. A power plant comprising: a compressor for compressing a mixture gas of steam and carbon dioxide so as to produce a working fluid; a combustor disposed downstream of said compressor and adapted to receive and burn oxygen, a reformed fuel mixture of hydrogen and carbon dioxide, and the working fluid produced by said compressor so as to produce a combustion gas; a gas turbine disposed downstream of said combustor and adapted to receive and expand the combustion gas produced by said combustor so as to produce an exhaust gas; a bottoming system disposed downstream of said gas turbine and including a condenser for receiving and condensing the exhaust gas from said gas turbine so as to produce water; a heat exchanger having an exhaust gas side disposed downstream of said gas turbine for receiving and cooling the exhaust gas produced by said gas turbine so as to produce the mixture gas to be compressed by said compressor, and having a water side disposed downstream of said bottoming system for heating the water condensed by said bottoming system by using the exhaust gas in said exhaust gas side so as to produce steam; a steam turbine disposed downstream of said water side of said heat exchanger for receiving and expanding the steam produced by said water side of said heat exchanger so as to produce exhaust steam, said steam turbine being disposed upstream of said combustor such that said combustor receives the exhaust steam produced by said steam turbine; a reformer having an exhaust gas side for receiving the exhaust gas from said gas turbine and a fuel side for receiving a fuel mixture of methanol and water, said reformer being adapted so that the fuel mixture of methanol and water in said fuel side is heated by using the exhaust gas in said exhaust gas side so as to produce the reformed fuel mixture of hydrogen and carbon dioxide, said fuel side of said reformer being disposed upstream of said combustor such that said combustor receives the reformed fuel mixture of hydrogen and carbon dioxide produced by said reformer; and a gas turbine cooling system for extracting a portion of the working fluid produced by said compressor and a portion of the exhaust steam produced by said steam turbine so as to produce a cooling medium, and for channeling the cooling medium into said gas turbine so as to cool said gas turbine.
 2. The power plant of claim 1, wherein said compressor comprises a low pressure compressor, a high pressure compressor, and a passage connecting said low pressure compressor and said high pressure compressor, said compressor further comprising an intercooler in said passage, said bottoming system and said intercooler being arranged such that a portion of the water produced by said bottoming system is supplied to said intercooler.
 3. The power plant of claim 2, further comprising a pressure pump between said bottoming system and said intercooler for feeding the water from said bottoming system to said intercooler under pressure.
 4. The power plant of claim 1, further comprising a regenerative heat exchanger having a working fluid side between said compressor and said combustor for receiving the working fluid from said compressor, and having an exhaust gas side between said gas turbine and said heat exchanger for receiving the exhaust gas from said gas turbine, said regenerative heat exchanger being adapted to heat the working fluid by using the exhaust gas in the exhaust gas side.
 5. The power plant of claim 4, wherein said compressor comprises a low pressure compressor, a high pressure compressor, and a passage connecting said low pressure compressor and said high pressure compressor, said compressor further comprising an intercooler in said passage, said bottoming system and said intercooler being arranged such that a portion of the water produced by said bottoming system is supplied to said intercooler.
 6. The power plant of claim 1, wherein said bottoming system includes a low pressure steam turbine upstream of said condenser such that said condenser receives and condenses steam from said low pressure steam turbine so as to produce water, an inlet of said low pressure turbine being disposed downstream of said gas turbine so as to receive the exhaust gas produced by said gas turbine.
 7. The power plant of claim 1, wherein said heat exchanger comprises: a first heat exchanger and a second heat exchanger arranged in series, each of said first heat exchanger and said second heat exchanger having an exhaust gas side disposed downstream of said gas turbine to cool exhaust gas produced by said gas turbine so as to produce the mixture gas to be compressed by said compressor, and each of said first heat exchanger and said second heat exchanger having a water side disposed downstream of said bottoming system to heat the water condensed by said bottoming system by using the exhaust gas in said exhaust gas side so as to produce steam.
 8. The power plant of claim 7, wherein said bottoming system includes a low pressure steam turbine having an inlet connected to an exhaust gas line between said exhaust gas side of said first heat exchanger and said exhaust gas side of said second heat exchanger so as to receive exhaust gas produced by said gas turbine and cooled by said first heat exchanger.
 9. The power plant of claim 7, wherein said exhaust gas side of said reformer is disposed between said exhaust gas side of said first heat exchanger and said exhaust gas side of said second heat exchanger. 